Canon 6D esposure control using auto iso
I have a Canon 6D and most of the time that I shoot video its nighttime. I have a manual lens on the camera and most of the time it is set wide open. I shoot at 24fps so shutter is at 1/50. I can lock it there with ML. Considering I have my aperture wide open and shutter has to stay at 1/50 I obviously have to control light with ISO. The problem im having is that I want to have a mode thats basically like a shutter AND aperture priority where the camera controls auto ISO however I still want to be able to control the exposure compensation. I have found that either i put it in manual mode set everything up and put it in auto ISO and the camera will adjust to 0 exposure compensation or I have to do it myself. Is there a mode or something im missing that will allow me to set my aperture and shutter and then allow the camera to auto adjust ISO according to my exposure compensation?